Jarek

22 hours ago, symmetal said:

Hi Jarek,

I started off with around 68mm like the GT102 but had quite bad elongated corner stars pointing towards the centre so kept adding distance until the corner distortion was minimized. I also had to add a tilt adjuster, as the 6200 is a full frame sensor, and I couldn't get left and right stars in focus at the same time. The final total back focus distance is now 78.5mm, which seems quite a bit longer than for the scopes listed on the WO 68III flattener page, but seems to work.

Your 1600 is a smaller sensor so the flattener spacing is not so critical for you but this may be helpful as a starting point. 🙂

Alan

Thanks a lot! I was going to have ca. 69mm and than get CCDInspector to experiment with. Yes, as 1600 has much smaller chip distance should be not so critical as for 6200. Also im trying to avoid tilt adjuster... 

Clear skies!

Hi, im quite new here but noticed setup similar to mine... Im using WO FLT98 with FF68III flattener and ASI1600.

Could you help how to calculate bacfocus for FLT98 and FF68III? Only i have are approx values... 

all best

Jarek